JP3243126B2 - Magneto-optical recording medium - Google Patents
Magneto-optical recording mediumInfo
- Publication number
- JP3243126B2 JP3243126B2 JP18951294A JP18951294A JP3243126B2 JP 3243126 B2 JP3243126 B2 JP 3243126B2 JP 18951294 A JP18951294 A JP 18951294A JP 18951294 A JP18951294 A JP 18951294A JP 3243126 B2 JP3243126 B2 JP 3243126B2
- Authority
- JP
- Japan
- Prior art keywords
- layer
- recording
- magnetic
- reproducing
- magnetization
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
- G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
- G11B11/10582—Record carriers characterised by the selection of the material or by the structure or form
- G11B11/10586—Record carriers characterised by the selection of the material or by the structure or form characterised by the selection of the material
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
- G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
- G11B11/10502—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing characterised by the transducing operation to be executed
- G11B11/10515—Reproducing
Description
【0001】[0001]
【産業上の利用分野】本発明は光磁気記録媒体、いわゆ
る光ディスクに係り、特に光ビームの空間周波数(再生
時の読出光の波長及び対物レンズの開口数により規定さ
れる周波数)を越える密度で情報を記録・再生するため
のいわゆる超解像による光磁気記録媒体に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium, that is, an optical disk, and more particularly to a medium having a density exceeding a spatial frequency of a light beam (a frequency defined by a wavelength of a reading light at the time of reproduction and a numerical aperture of an objective lens). The present invention relates to a so-called super-resolution magneto-optical recording medium for recording and reproducing information.
【0002】[0002]
【従来の技術】従来から、光ディスクにおける超解像再
生として、幾つかの読出方式が開発されている。特に、
光スポットの温度分布を利用して情報の読出しを行うF
AD(Front Aperture Detection)とRAD(Rear Ape
rture Detection )が代表的である。2. Description of the Related Art Conventionally, several reading methods have been developed for super-resolution reproduction on an optical disk. In particular,
F for reading information using the temperature distribution of the light spot
AD (Front Aperture Detection) and RAD (Rear Ape
rture Detection) is typical.
【0003】図6に従来のFAD再生を行うための光デ
ィスクの構造を示す。図6(A)は、第1の従来例(光
ディスク1’)であり、図6(B)は第1の従来例によ
る光ディスクを改良した第2の従来例(光ディスク
1”)である。FIG. 6 shows a structure of an optical disk for performing a conventional FAD reproduction. FIG. 6A shows a first conventional example (optical disc 1 ′), and FIG. 6B shows a second conventional example (optical disc 1 ″) obtained by improving the optical disc according to the first conventional example.
【0004】図6(A)及び(B)において、下地層5
2、62及び保護層56、66は磁性層を保護する。再
生層53、63はPt/Co積層膜で組成されており、
内部磁化の向きに応じて基板側から照射される読出光の
偏光面回転を行う。中間層54、64は再生層53、6
3及び記録層55、65と磁気的に交換結合されてい
る。また、中間層54、64はキュリー温度が低く、再
生中に照射される光スポットの高温領域において磁化が
消失する。記録層55、65は記録時に所定の向きに磁
化される。In FIGS. 6A and 6B, an underlayer 5 is formed.
2, 62 and the protective layers 56, 66 protect the magnetic layer. The reproducing layers 53 and 63 are composed of a Pt / Co laminated film,
The plane of polarization of the read light emitted from the substrate side is rotated according to the direction of the internal magnetization. The intermediate layers 54 and 64 are the reproduction layers 53 and 6
3 and the recording layers 55 and 65 are magnetically exchange-coupled. Further, the intermediate layers 54 and 64 have a low Curie temperature, and the magnetization disappears in a high-temperature region of a light spot irradiated during reproduction. The recording layers 55 and 65 are magnetized in a predetermined direction during recording.
【0005】図7に上記従来の光ディスクを用いたとき
に光スポットにより生ずる温度分布の様子を示す。図7
に示すように、読出光の照射に伴い円形の光スポットL
Bの中心を極大点とした光の強度分布が生ずる。一方、
光ディスクの表面に生ずる温度分布の極大点は、光スポ
ットの進行方向から若干後方にずれた位置に生ずる。F
ADは光スポットの温度分布のうち比較的温度の低い光
スポットLBの前半部(低温領域AL )を利用して再生
を行う再生方法である。FIG. 7 shows a temperature distribution generated by a light spot when the above-mentioned conventional optical disk is used. FIG.
As shown in FIG.
A light intensity distribution having a maximum point at the center of B occurs. on the other hand,
The maximum point of the temperature distribution generated on the surface of the optical disk occurs at a position slightly backward from the traveling direction of the light spot. F
AD is a reproduction method for performing reproduction by using the first half (low-temperature area A L ) of the light spot LB having a relatively low temperature in the temperature distribution of the light spot.
【0006】光スポットLBが照射されると光ディスク
1’及び1”の表面温度及び各磁性層の温度が上昇す
る。低温領域AL では、中間層54、64はキュリー温
度に達していないので磁化が消失せず、中間層54、6
4は再生層53、63及び記録層55、65間の交換結
合力を伝達する。このため、記録層55、65の磁区の
磁化の向きは中間層54、64を通して再生層53、6
3に伝達される。When the light spot LB is irradiated, the surface temperatures of the optical disks 1 'and 1 "and the temperatures of the respective magnetic layers rise. In the low temperature region A L , the intermediate layers 54 and 64 do not reach the Curie temperature, and thus have magnetization. Does not disappear, and the intermediate layers 54 and 6
4 transmits the exchange coupling force between the reproducing layers 53 and 63 and the recording layers 55 and 65. Therefore, the magnetization directions of the magnetic domains of the recording layers 55 and 65 are changed through the intermediate layers 54 and 64 to the reproduction layers 53 and 6.
3 is transmitted.
【0007】ところが、光スポットLBの後半部(高温
領域AH )はさらに温度が高くなり、高温領域AH にお
いて中間層54、64はキュリー温度を越えて磁化が消
失する。磁化が消失すると交換結合力も消失する。例え
ば、中間層54、64の組成を、Dy22(Fe90C
o10)78〔at% 〕とすると、磁化が消失する温度は約1
50℃となる。このため、記録層55、65の磁化の向
きは再生層53、63に伝達されることがなくなり、再
生層53、63の磁化の向きは外部から与えられる再生
磁界の方に向く。則ち、高温領域AH からは情報を再生
することができなくなり、マスク領域として働くことに
なる。However, the temperature of the latter half of the light spot LB (high-temperature region A H ) is further increased, and in the high-temperature region A H , the magnetization of the intermediate layers 54 and 64 exceeds the Curie temperature and disappears. When the magnetization disappears, the exchange coupling force also disappears. For example, the composition of the intermediate layers 54 and 64 is changed to Dy 22 (Fe 90 C
o 10 ) Assuming 78 [at%], the temperature at which the magnetization disappears is about 1
It will be 50 ° C. Therefore, the directions of magnetization of the recording layers 55 and 65 are not transmitted to the reproducing layers 53 and 63, and the directions of magnetization of the reproducing layers 53 and 63 are directed to the reproducing magnetic field applied from the outside. Sokuchi, it becomes impossible to reproduce information from the high-temperature region A H, it will act as a mask region.
【0008】光スポットが通過し再び低温となると中間
層54、64の磁化が発生するに従い、記録層55、6
5の磁化の向きが再生層53、63に伝達され、次回の
再生に備える。When the light spot passes through and becomes low temperature again, as the magnetization of the intermediate layers 54 and 64 is generated, the recording layers 55 and 6 are generated.
The direction of magnetization of No. 5 is transmitted to the reproducing layers 53 and 63 to prepare for the next reproduction.
【0009】図8に第1の従来例の光ディスク1’にお
けるカー回転角のヒステリシス特性を示す。通常、記録
層の磁化を再生層に転写するための必要条件は、両者の
交換結合力をHWpb 、再生層の保磁力をHCpb とする
と、 HWpb >HCpb …(1) なる関係が必要であり、実用上十分なC/N(carrier-
to-noise ratio)を得るためには、HWpb −HCpb が1
〔kOe〕以上であること、が必要とされる。しかしな
がら、第1の従来例では、図8のは再生層(Pt/C
o多層膜)のヒステリシス特性であるが、HWpb −H
Cpb が約0.7〔kOe〕しかなく、十分なC/Nが得
られない。FIG. 8 shows the hysteresis characteristic of the Kerr rotation angle of the first conventional optical disc 1 '. Usually, the requirements for transferring the magnetization of the recording layer to the reproducing layer, the exchange coupling force therebetween H Wpb, when the coercive force of the reproducing layer and H Cpb, H Wpb> H Cpb ... (1) the relationship is Necessary and practically sufficient C / N (carrier-
To obtain a to-noise ratio) is, H Wpb -H Cpb 1
[KOe] or more is required. However, in the first conventional example, FIG. 8 shows the reproduction layer (Pt / C
o Wpb -H
Cpb is only about 0.7 [kOe], and a sufficient C / N cannot be obtained.
【0010】この原因としては、図8にから判るよう
に、根本的に再生層と中間層との交換結合力HW が弱い
といえる。則ち、交換結合力HW は成膜条件や組成によ
り影響を受けるが、第1の従来例の光ディスク1’の場
合は、中間層の組成であるTbFeは再生層のPt/C
o積層膜との間での交換結合力が十分に働かないのであ
る。これに対処するためには、中間層の組成を調整する
必要がある。[0010] As the reason, as can be seen from the two Fig. 8, it can be said that the exchange coupling force H W with fundamentally reproducing layer and the intermediate layer is weak. That is, the exchange coupling force HW is affected by the film formation conditions and composition, but in the case of the optical disk 1 'of the first conventional example, the composition of the intermediate layer, TbFe, is the Pt / C of the reproducing layer.
o The exchange coupling force with the laminated film does not work sufficiently. To cope with this, it is necessary to adjust the composition of the intermediate layer.
【0011】これを改良するために、中間層の組成を調
整したものが第2の従来例である。図9に第2の従来例
の光ディスク1”におけるカー回転角のヒステリシス特
性を示す。図9に示すように、の再生層(Pt/Co
多層膜)のヒステリシス特性において、HWpb −HCpb
が約2.6〔kOe〕程度であり、記録層と中間層の交
換結合力は十分であることが判る。In order to improve this, the composition of the intermediate layer is adjusted in a second conventional example. FIG. 9 shows the hysteresis characteristic of the Kerr rotation angle of the optical disc 1 "of the second conventional example. As shown in FIG.
In the hysteresis characteristics of the multilayer film), H Wpb -H Cpb
Is about 2.6 [kOe], which indicates that the exchange coupling force between the recording layer and the intermediate layer is sufficient.
【0012】[0012]
【発明が解決しようとする課題】しかしながら、上記第
2の従来例による光ディスクでは、中間層と再生層の交
換結合力は十分にも拘らず、実際にC/Nを測定してみ
ると十分な特性が得られていない。However, in the optical disk according to the second conventional example, although the exchange coupling force between the intermediate layer and the reproducing layer is sufficient, when the C / N is actually measured, it is not sufficient. Characteristics have not been obtained.
【0013】上記のC/Nは、例えば、下記に示す条件
において、第1の従来例の光ディスクにおいて34〔d
B〕、第2の従来例の光ディスクにおいて25〔dB〕と
いう値が測定されている。The above C / N is, for example, 34 [d in the first conventional optical disc under the following conditions.
B], a value of 25 [dB] is measured in the second conventional optical disc.
【0014】C/N特性測定条件 波長λ 680〔nm〕 開口数NA 0.55 線速度 4.24〔m/s 〕 記録情報周波数 5.3〔MHz 〕 マーク長 0.4〔μm 〕 書込レーザ出力Pw 5.5〔mW〕 記録磁界の強さHw 500〔Oe〕 読出レーザ出力Pr 2.0〔mW〕 再生磁界の強さHr 600〔Oe〕 本来、光ディスクの理想的な再生特性として40〔dB〕
程度のC/Nが必要であるとされているので、これら従
来の光ディスクでは十分な特性を有していない。 C / N characteristic measurement conditions Wavelength λ 680 [nm] Numerical aperture NA 0.55 Linear velocity 4.24 [m / s] Recording information frequency 5.3 [MHz] Mark length 0.4 [μm] Writing Laser output P w 5.5 [mW] Recording magnetic field strength H w 500 [Oe] Reading laser output P r 2.0 [mW] Reproduction magnetic field strength H r 600 [Oe] Originally ideal for optical discs 40 [dB] as reproduction characteristics
These conventional optical discs do not have sufficient characteristics because it is said that a certain degree of C / N is required.
【0015】この原因を以下に考察する。図9を観察す
ると、第2の従来例において、2つのヒステリシスルー
プが重なっていることが判る。図9において、は再生
層のヒステリシスループである。この再生層のヒステリ
シスループに他のヒステリシスループが重なってい
る。このの特性は、中間層のヒステリシス特性であ
る。このことより中間層は記録層よりも再生層とより強
く交換結合していることが判る。これは中間層が高温領
域で一度磁化が消失し再び低温になり磁化が発生する
時、その磁化の向きが記録層の磁化の向きではなく、再
生層の有する再生磁界の向きに一様に揃ってしまうこと
を意味している。この結果、低温領域においても記録層
の磁化の向きが再生層に十分に伝達されないことによ
り、好適なC/Nが得られないのである。The cause will be discussed below. Observation of FIG. 9 shows that two hysteresis loops overlap in the second conventional example. FIG. 9 shows a hysteresis loop of the reproducing layer. Another hysteresis loop overlaps the hysteresis loop of the reproducing layer. This characteristic is the hysteresis characteristic of the intermediate layer. This indicates that the intermediate layer is more strongly exchange-coupled to the reproducing layer than to the recording layer. This is because when the magnetization of the intermediate layer once disappears in the high-temperature region and becomes low-temperature again, and the magnetization occurs, the direction of the magnetization is uniformly aligned not with the direction of the magnetization of the recording layer but with the direction of the reproducing magnetic field of the reproducing layer. Means that As a result, even in the low-temperature region, the magnetization direction of the recording layer is not sufficiently transmitted to the reproducing layer, so that a suitable C / N cannot be obtained.
【0016】そこで、本発明の目的は、C/Nの良好な
特性を示す光磁気記録媒体を提供することにある。An object of the present invention is to provide a magneto-optical recording medium exhibiting good C / N characteristics.
【0017】[0017]
【課題を解決するための手段】上記目的を達成するため
には、再生層と中間層との交換結合力の大きさを一定水
準に保ちつつ、中間層と記録層の交換結合力を大きく
し、相対的に後者の方を大きくする必要がある。In order to achieve the above object, the exchange coupling force between the intermediate layer and the recording layer is increased while maintaining the exchange coupling force between the reproducing layer and the intermediate layer at a constant level. It is necessary to make the latter relatively larger.
【0018】図9において、再生層の保磁力をHCpb 、
交換結合力をHWpb 、中間層の保磁力をHCmd 、交換結
合力をHWmd とすると、光磁気記録媒体が十分なC/N
を得るためには、 HWpb +HCpb <HWmd −HCmd …(2) の関係を有することが必要とされる。第2の従来例の光
ディスクに式(2)の関係を持たせるためには、中間層
と記録層の交換結合力HWmd を上昇させればよい。In FIG. 9, the coercive force of the reproducing layer is H Cpb ,
Assuming that the exchange coupling force is H Wpb , the coercive force of the intermediate layer is H Cmd , and the exchange coupling force is H Wmd , the magneto-optical recording medium has a sufficient C / N ratio.
In order to obtain, it is necessary to have a relationship of H Wpb + H Cpb <H Wmd -H Cmd ... (2). In order to make the optical disk of the second conventional example have the relationship of equation (2), the exchange coupling force H Wmd between the intermediate layer and the recording layer may be increased.
【0019】一般に、互いに接する二つの磁性層間に働
く交換結合力は、双方の組成のうち共通する強磁性元素
の相互作用である。第2の従来例において、中間層と記
録層の組成を比べると、強い相互作用があるのは遷移金
属の鉄(Fe)、コバルト(Co)だけで希土類からの
強い相互作用はない。よって、第2の従来例の光ディス
クでは、中間層と記録層とが同じ希土類−遷移金属の合
金からなるフェリ磁性体であるにも拘らず、十分な交換
結合力が働かなかったものと推測される。In general, the exchange coupling force acting between two magnetic layers in contact with each other is an interaction of a common ferromagnetic element in both compositions. In the second conventional example, when the compositions of the intermediate layer and the recording layer are compared, only the transition metals iron (Fe) and cobalt (Co) have strong interaction, and there is no strong interaction from rare earth. Therefore, it is presumed that in the optical disk of the second conventional example, a sufficient exchange coupling force did not work despite the fact that the intermediate layer and the recording layer were ferrimagnetic materials made of the same rare earth-transition metal alloy. You.
【0020】従って、異なる希土類元素を有する2つの
層の間に、双方の希土類元素を共に具備する磁性層を挿
入すれば、異なる組成を有する2層の間の磁気的な交換
結合力が増大することが期待できる。Therefore, if a magnetic layer having both rare earth elements is inserted between two layers having different rare earth elements, the magnetic exchange coupling force between the two layers having different compositions increases. I can expect that.
【0021】そこで、本願発明の光磁気記録媒体は、プ
ラチナ(Pt)を主成分とする金属とコバルト(Co)
を主成分とする金属との積層構造又はプラチナ(Pt)
及びコバルト(Co)を主成分とする合金構造からなる
読出光の照射側に位置する磁性層を有する光磁気記録媒
体であって、ジスプロシウム(Dy)を主成分とする希
土類と、鉄(Fe)及びコバルト(Co)を主成分とす
る遷移金属との合金を主成分とし第1のキュリー温度T
C1を有する第1の磁性層と、テルビウム(Tb)を主成
分とする希土類と、鉄(Fe)及びコバルト(Co)を
主成分とする遷移金属と、の合金を主成分とし第2のキ
ュリー温度TC2を有する第2の磁性層と、ジスプロシウ
ム(Dy)及びテルビウム(Tb)を共に含有する希土
類と、鉄(Fe)及びコバルト(Co)を主成分とする
遷移金属と、の合金を主成分とし第3のキュリー温度T
C3を有し第1の磁性層と第2の磁性層との間に介装され
る第3の磁性層と、を有し、第1の磁性層のキュリー温
度TC1、第2の磁性層のキュリー温度TC2、第3の磁性
層のキュリー温度TC3及び再生温度Tpbとの間にT C1<
Tpb<TC2かつTC1≦TC3≦TC2なる関係を有する。Therefore, the magneto-optical recording medium of the present invention is
Metals mainly composed of platinum (Pt) and cobalt (Co)
Structure of platinum or metal (Pt)
And an alloy structure mainly composed of cobalt (Co)
Magneto-optical recording medium having magnetic layer positioned on irradiation side of read light
A rare body containing dysprosium (Dy) as a main component
Earth and iron (Fe) and cobalt (Co) as main components
The first Curie temperature T mainly containing an alloy with a transition metal
C1And a first magnetic layer having terbium (Tb).
Rare earth and iron (Fe) and cobalt (Co)
A second key mainly composed of an alloy of a transition metal and a main component;
Curie temperature TC2A second magnetic layer having
Earth containing both terbium (Ty) and terbium (Tb)
And iron (Fe) and cobalt (Co) as main components
A third Curie temperature T mainly containing an alloy of a transition metal and
C3And is interposed between the first magnetic layer and the second magnetic layer.
A third magnetic layer, and the Curie temperature of the first magnetic layer.
Degree TC1, Curie temperature T of the second magnetic layerC2, The third magnetism
Curie temperature T of the layerC3And regeneration temperature TpbBetween T C1<
Tpb<TC2And TC1≤TC3≤TC2Have the relationship
【0022】[0022]
【作用】本願発明を図1の再生原理図に参照しながら説
明する。図1は各磁性層の磁化の向きを矢印で示したも
のである。図1に示すように、再生層4は状態変化層と
して働く。再生層4は読出光の照射側に位置する磁性層
に相当し、中間層5は第1の磁性層に相当する。記録層
7は第2の磁性層に相当し、中間補助層6は第3の磁性
層に相当する。中間補助層6(第3の磁性層)は、中間
層5(第1の磁性層)及び記録層7(第2の磁性層)と
同じフェリ磁性体である。また、中間補助層6はジスプ
ロシウム(Dy)及びテルビウム(Tb)を含有するの
で、中間層5及び記録層7を磁気的に交換結合し、記録
層7の磁化を中間層5に転写する。The present invention will be described with reference to the reproduction principle diagram of FIG. FIG. 1 shows the directions of magnetization of the respective magnetic layers by arrows. As shown in FIG. 1, the reproducing layer 4 functions as a state change layer. The reproducing layer 4 corresponds to a magnetic layer located on the irradiation side of the reading light, and the intermediate layer 5 corresponds to a first magnetic layer. The recording layer 7 corresponds to a second magnetic layer, and the intermediate auxiliary layer 6 corresponds to a third magnetic layer. The intermediate auxiliary layer 6 (third magnetic layer) is the same ferrimagnetic material as the intermediate layer 5 (first magnetic layer) and the recording layer 7 (second magnetic layer). Since the intermediate auxiliary layer 6 contains dysprosium (Dy) and terbium (Tb), the intermediate layer 5 and the recording layer 7 are magnetically exchange-coupled, and the magnetization of the recording layer 7 is transferred to the intermediate layer 5.
【0023】各磁性層において、下向きの矢印は記録情
報‘0’を保有する磁区を示し、上向きの矢印は記録情
報‘1’を保有する磁区を示す。記録層7は自らの保磁
力を越える強い外部磁界により、記録情報が磁化の向き
として記録される。In each magnetic layer, a downward arrow indicates a magnetic domain holding recording information '0', and an upward arrow indicates a magnetic domain holding recording information '1'. The recording information is recorded in the recording layer 7 as a magnetization direction by a strong external magnetic field exceeding its own coercive force.
【0024】再生時、外部から再生磁界Hpbが印加され
る。光スポットLBが光ディスクに照射されない領域で
は、記録層7の磁化は、本発明に係る中間補助層6の作
用による強い交換結合力により、中間層5及び再生層4
に転写される。During reproduction, a reproduction magnetic field Hpb is applied from the outside. In a region where the light spot LB is not irradiated onto the optical disc, the magnetization of the recording layer 7 is changed by the strong exchange coupling force due to the action of the intermediate auxiliary layer 6 according to the present invention.
Is transferred to
【0025】光ディスク1が回転し、光スポットLBが
光ディスク1に照射されると、ディスクの表面温度が、
図7の温度上昇曲線に示すように上昇する。光スポット
LBの前半部は温度上昇の低い低温領域AL である。こ
の領域では、中間層5のキュリー温度TC2以下であり交
換結合力は断たれないので、記録層7の磁化が再生層4
に転写される。When the optical disk 1 rotates and the light spot LB is irradiated on the optical disk 1, the surface temperature of the disk becomes
It rises as shown by the temperature rise curve in FIG. The first half of the light spot LB is a low temperature area A L where the temperature rise is low. In this region, since the exchange coupling force is not cut off since the Curie temperature T C2 of the intermediate layer 5 is lower than that, the magnetization of the recording layer 7 is
Is transferred to
【0026】また、光スポットLBの後半部は高温領域
AH になっている。このとき、中間層5の温度はキュリ
ー温度TC2以上となり、磁化が消失する。磁化が消失す
ると、再生層4の磁化の向きを規定していた交換結合力
がなくなる。再生層4の磁化の向きは再生磁界Hpbの方
向に常に向く。低温領域AL の磁化の状態は、記録情報
としては‘0’となり、実際には情報が読出せない状
態、則ち、マスクがなされたことと等価となる。[0026] In addition, the second half of the light spot LB is in the high temperature area A H. At this time, the temperature of the intermediate layer 5 becomes equal to or higher than the Curie temperature T C2 , and the magnetization disappears. When the magnetization disappears, the exchange coupling force that defines the direction of the magnetization of the reproducing layer 4 disappears. The direction of magnetization of the reproducing layer 4 always faces the direction of the reproducing magnetic field Hpb . The state of magnetization in the low temperature region A L is “0” as recorded information, which is equivalent to a state where information cannot be actually read, that is, a mask has been made.
【0027】さらに光スポットLBが通過してしまう
と、中間層5の温度はキュリー温度T C2以下になる。こ
のときの中間層5の磁化の向きは、中間補助層6の作用
により記録層7の磁化の向きがそのまま転写される。中
間層5に磁区が生ずると、中間層5と再生層4との交換
結合力により、再生層4の磁化が記録層7の磁化の向き
と同じになる。Further, the light spot LB passes.
And the temperature of the intermediate layer 5 is the Curie temperature T C2It becomes below. This
The direction of magnetization of the intermediate layer 5 at the time of
As a result, the direction of the magnetization of the recording layer 7 is transferred as it is. During ~
When a magnetic domain is generated in the intermediate layer 5, the exchange between the intermediate layer 5 and the reproducing layer 4 is performed.
Due to the coupling force, the magnetization of the reproducing layer 4 changes the direction of the magnetization of the recording layer 7.
Will be the same as
【0028】以上のように、本願発明の光磁気記録媒体
によれば、中間補助層6を介したことにより、再生層4
と中間層5の交換結合力を十分に大きく保ったまま記録
層7と中間層5の交換結合力がより高まるので、記録層
7から再生層4への磁化の転写を良好に行うことができ
る。このため、再生装置はこのFAD方式に基づく再生
において、高い分離度で情報を分離でき、C/Nが向上
する。As described above, according to the magneto-optical recording medium of the present invention, since the intermediate auxiliary layer 6 is interposed, the reproducing layer 4
Since the exchange coupling force between the recording layer 7 and the intermediate layer 5 is further increased while maintaining the exchange coupling force between the recording layer 7 and the intermediate layer 5 sufficiently large, the transfer of the magnetization from the recording layer 7 to the reproducing layer 4 can be favorably performed. . Therefore, in the reproduction based on the FAD method, the reproduction apparatus can separate information with a high degree of separation, and C / N is improved.
【0029】[0029]
【実施例】次に、本発明の好適な実施例を図面を参照し
て説明する。 (i)第1実施例 図2に本発明の第1実施例の光ディスクを示す。Next, a preferred embodiment of the present invention will be described with reference to the drawings. (I) First Embodiment FIG. 2 shows an optical disc according to a first embodiment of the present invention.
【0030】図2に示すように、第1実施例の光ディス
ク1は、表面を保護し光を透過する基板2と、磁性膜を
保護し光を透過する下地層3と、再生時に光スポットの
照射により内部磁化の向きに合わせて読出光の偏光面回
転を行う再生層4と、再生層4と記録層7との交換結合
力を伝達し光スポットの高温領域で磁化が消失する中間
層5と、中間層5と記録層7との間に磁気的交換結合力
を伝達する本発明の特徴である中間補助層6と、高い保
磁力を示し記録時に記録磁界により磁化される記録層7
と、記録層7を保護する保護膜8と、を備える。As shown in FIG. 2, the optical disk 1 of the first embodiment has a substrate 2 for protecting the surface and transmitting light, an underlayer 3 for protecting the magnetic film and transmitting light, and a light spot for reproducing light. A reproducing layer 4 that rotates the plane of polarization of read light in accordance with the direction of internal magnetization by irradiation, and an intermediate layer 5 that transmits exchange coupling force between the reproducing layer 4 and the recording layer 7 and loses magnetization in a high-temperature region of a light spot. An intermediate auxiliary layer 6 which is a feature of the present invention for transmitting a magnetic exchange coupling force between the intermediate layer 5 and the recording layer 7; and a recording layer 7 which exhibits a high coercive force and is magnetized by a recording magnetic field during recording.
And a protective film 8 for protecting the recording layer 7.
【0031】次に各膜の組成について説明する。下地層
3及び保護層8は、再生層4以下の膜を保護する働きを
する。また、下地膜3は、生成層4によるカー回転角を
向上させるという働きもある。下地層3及び保護層8の
膜の性質としては、光学的に影響を与えることがなく、
透明であって水分等を透過させない緻密な組成を有する
必要がある。下地層3及び保護層8の組成としては、図
1のSiNの他、AlN、Ta2 O5 等が使用可能であ
る。膜厚としては、経年変化や酸化に対して抵抗できる
程度の厚さ(例えば、20〔nm〕程度)以上の厚さは必
要で、熱伝導特性や光透過特性に影響を与えない程度の
厚さ(例えば、100〔nm〕程度)であることが好まし
い。Next, the composition of each film will be described. The underlayer 3 and the protective layer 8 function to protect films below the reproducing layer 4. The base film 3 also has a function of improving the Kerr rotation angle by the generation layer 4. The properties of the underlayer 3 and the protective layer 8 do not affect optically.
It is necessary to have a dense composition that is transparent and does not transmit moisture or the like. As the composition of the underlayer 3 and the protective layer 8, AlN, Ta 2 O 5 or the like can be used in addition to SiN of FIG. The film must have a thickness (for example, about 20 [nm]) or more that can resist aging and oxidation, and a thickness that does not affect the heat conduction characteristics and the light transmission characteristics. (For example, about 100 [nm]).
【0032】再生層4は、光ビームの偏光面を回転させ
るいわゆるカー回転を生じさせる状態変化層として働
く。再生層4の膜の性質としては、光ビームの照射によ
り垂直磁化となってカー効果またはファラデー効果に代
表される磁気光学的性質を示し、内部磁化の向きに対応
して偏光面回転の回転角が変化する必要がある。再生層
4の組成としては、図1のプラチナ−コバルト積層膜
(Pt/Co)の他に、Pt−Co合金、GdFeCo
の組成を有するフェリ磁性体等を用いることも可能であ
る。再生層4の膜厚としては、カー効果を利用するため
に膜自体の反射率が40%程度となる膜厚(例えば、8
〔nm〕程度)以上であって、膜の磁性的性質が垂直磁化
膜を保有できる程度の膜厚(例えば、30〔nm〕程度)
以下であることが好ましい。The reproducing layer 4 functions as a state change layer that causes a so-called Kerr rotation that rotates the plane of polarization of the light beam. The properties of the film of the reproducing layer 4 are perpendicular magnetization upon irradiation with a light beam, exhibit magneto-optical properties typified by the Kerr effect or the Faraday effect, and indicate the rotation angle of the polarization plane rotation corresponding to the direction of the internal magnetization. Need to change. As the composition of the reproducing layer 4, in addition to the platinum-cobalt laminated film (Pt / Co) of FIG. 1, a Pt—Co alloy, GdFeCo
It is also possible to use a ferrimagnetic material having the following composition. The thickness of the reproducing layer 4 is such that the reflectivity of the film itself is about 40% in order to utilize the Kerr effect (for example, 8
[Nm]) or more, and the film has a magnetic property such that the magnetic property of the film can hold a perpendicular magnetization film (for example, about 30 [nm]).
The following is preferred.
【0033】中間層5は、再生温度Tpbより高いマスク
領域(高温領域AH )において、再生層4と記録層6と
の交換結合力を切断する働きをする。中間層5の膜の性
質としては、光スポットの低温領域では垂直磁化を保有
して交換結合力を伝え、光スポットの高温領域でキュリ
ー点に達し、磁区を消失させる。そのため、図7に示す
光スポットの低温領域AL と高温領域AH との境界付近
の温度(再生温度Tpb:例えば、100〜150℃)以
下であることが、中間層5の有するキュリー温度TC2に
求められる。中間層5の組成としては、Dy等を主成分
とする希土類と、FeCo等を主成分とする遷移金属と
からなる合金が好ましい。中間層5の膜厚としては、中
間層5がキュリー点に達したとき、再生層4と記録層7
との交換結合力を断つのに十分な厚さ(例えば、5〔n
m〕程度以上)を有し、磁区が記録層7から再生層4に
転写される際に効率がよく、記録感度を落とさない程度
の厚さ(例えば、30〔nm〕程度)以下であることが好
ましい。The intermediate layer 5 has a function of cutting the exchange coupling force between the reproducing layer 4 and the recording layer 6 in a mask region (high-temperature region A H ) higher than the reproducing temperature T pb . As a property of the film of the intermediate layer 5, in the low temperature region of the light spot, the film retains perpendicular magnetization and transmits exchange coupling force, reaches the Curie point in the high temperature region of the light spot, and eliminates magnetic domains. Therefore, the Curie temperature of the intermediate layer 5 should be lower than or equal to the temperature (reproduction temperature T pb : for example, 100 to 150 ° C.) near the boundary between the low temperature area AL and the high temperature area A H of the light spot shown in FIG. Required for TC2 . As a composition of the intermediate layer 5, an alloy composed of a rare earth mainly composed of Dy or the like and a transition metal mainly composed of FeCo or the like is preferable. When the intermediate layer 5 reaches the Curie point, the reproducing layer 4 and the recording layer 7
Thickness sufficient to break the exchange coupling force with
m] or more, and is effective when the magnetic domain is transferred from the recording layer 7 to the reproducing layer 4 and has a thickness (for example, about 30 [nm]) or less that does not lower the recording sensitivity. Is preferred.
【0034】記録層7は、記録時に外部磁界で磁化され
る。記録層7の膜の性質としては、自らの磁区を再生層
4が保有する磁化の影響を受けず、また、光スポットの
最高温度でも磁化が消失しない性質が必要とされる。記
録層7の組成としては、Tb等を主成分とする希土類と
FeCo等を主成分とする遷移金属とからなる合金であ
ることが好ましく、例えば、図1のTbFeCoの組成
の他、GdTbFeCo、GdDyFeCo、NdDy
FeCo等が使用される。記録層7の膜厚としては、磁
区を再生層の磁化の向きによらず安定して存在させるた
めに必要な厚さ(例えば、30〔nm〕程度以上)であっ
て、記録感度を落とさない程度の厚さ(例えば、100
〔nm〕程度以下)であることが好ましい。The recording layer 7 is magnetized by an external magnetic field during recording. The properties of the film of the recording layer 7 need to be such that its magnetic domains are not affected by the magnetization possessed by the reproducing layer 4 and that the magnetization does not disappear even at the maximum temperature of the light spot. The composition of the recording layer 7 is preferably an alloy composed of a rare earth mainly composed of Tb or the like and a transition metal mainly composed of FeCo or the like. For example, in addition to the composition of TbFeCo in FIG. 1, GdTbFeCo, GdDyFeCo , NdDy
FeCo or the like is used. The film thickness of the recording layer 7 is a thickness (for example, about 30 [nm] or more) necessary for allowing magnetic domains to exist stably regardless of the direction of magnetization of the reproducing layer, and does not lower the recording sensitivity. Thickness (eg, 100
[Nm] or less).
【0035】上記した再生層4、中間層5及び記録層7
は、合金の組成が重要である。再生層4のキュリー温度
をTC0、中間層5のキュリー温度をTC1、記録層7のキ
ュリー温度をTC2とすると、 TC1<TC2<TC0 …(3) の関係を有する。The above-mentioned reproducing layer 4, intermediate layer 5, and recording layer 7
The composition of the alloy is important. Assuming that the Curie temperature of the reproducing layer 4 is T C0 , the Curie temperature of the intermediate layer 5 is T C1 , and the Curie temperature of the recording layer 7 is T C2 , there is a relationship of T C1 <T C2 <T C0 (3).
【0036】さて、本発明の中間補助膜6は、中間層5
と記録層7との間に設けられる。中間補助層6は、交換
結合力の弱い中間層5と記録層7との間に磁気的交換結
合力を有し記録層7の磁化を中間層5、再生層4に効率
よく転写させるために設けられる。中間補助層6の膜の
性質としては、中間層5と記録層7との間に良好な交換
結合力が働くことが要求される。この性質を有するため
に、光スポットLBの高温領域AH と低温領域AL との
境界温度(再生温度Tpb)とし、中間補助層6のキュリ
ー温度をTC3とすると、中間層5のキュリー温度TC1と
記録層のキュリー温度TC2との間には、 TC1<Tpb<TC2かつTC1≦TC3≦TC2 …(4) の関係があることが要求される。Now, the intermediate auxiliary film 6 of the present invention comprises the intermediate layer 5
And the recording layer 7. The intermediate auxiliary layer 6 has a magnetic exchange coupling force between the intermediate layer 5 having a low exchange coupling force and the recording layer 7 and efficiently transfers the magnetization of the recording layer 7 to the intermediate layer 5 and the reproducing layer 4. Provided. The properties of the intermediate auxiliary layer 6 require that a good exchange coupling force acts between the intermediate layer 5 and the recording layer 7. In order to have this property, assuming that the boundary temperature (reproduction temperature T pb ) between the high temperature area A H and the low temperature area A L of the light spot LB and the Curie temperature of the intermediate auxiliary layer 6 is T C3 , the Curie temperature of the intermediate layer 5 is It is required that the following relationship be established between the temperature T C1 and the Curie temperature T C2 of the recording layer: T C1 <T pb <T C2 and T C1 ≦ T C3 ≦ T C2 .
【0037】中間補助層6の組成としては、交換結合力
を伝達するため、中間層5の組成成分と記録層7の組成
成分の双方を含むことが必要とされる。則ち、本実施例
の中間層5と記録層7の組成では、双方の組成を含むT
bDyFeCoからなる合金である必要がある。The composition of the intermediate auxiliary layer 6 needs to include both the components of the intermediate layer 5 and the components of the recording layer 7 in order to transmit the exchange coupling force. That is, in the composition of the intermediate layer 5 and the recording layer 7 in this embodiment, T
The alloy must be made of bDyFeCo.
【0038】中間補助層6の膜厚としては、中間層と記
録層に交換結合力を伝達するのに十分な膜厚として、製
造上生成できる範囲で最も薄い厚さ(例えば、3〔nm〕
程度)以上であって、記録感度に悪影響を与えない程度
の厚さ(例えば、30〔nm〕程度)以下であることが好
ましい。The thickness of the intermediate auxiliary layer 6 is set to a thickness sufficient to transmit the exchange coupling force between the intermediate layer and the recording layer, and is set to the smallest thickness (for example, 3 nm) that can be produced in manufacturing.
) Or more, but not more than a thickness that does not adversely affect the recording sensitivity (for example, about 30 [nm]).
【0039】以上の条件の下、式(3)及び(4)を満
たす範囲で具体的な組成及び膜厚を表1にまとめて示
す。Under the above conditions, specific compositions and film thicknesses are shown in Table 1 within a range satisfying the equations (3) and (4).
【0040】[0040]
【表1】 図2では、第1実施例の中間補助層の好ましい特性を示
す組成として、上記範囲の中から (Tb50Dy50)19(Fe90Co10)81〔at% 〕 …(5) を挙げてある。[Table 1] In FIG. 2, (Tb 50 Dy 50 ) 19 (Fe 90 Co 10 ) 81 [at%] (5) is listed as a composition showing preferable characteristics of the intermediate auxiliary layer of the first embodiment. is there.
【0041】なお、組成式中の数値は2種の合金の原子
数量比を表すもので、原子パーセントという。例えば、 An Bm 〔at% 〕 という表示では、 n +m =100 であり、この式は、全原子の個数中n%のA原子および
m%のB原子によってこの物質が組成されることを意味
する。The numerical values in the composition formula represent the atomic ratio of the two alloys and are called atomic percent. For example, the indication that A n B m [at%], a n + m = 100, this equation is that this material is a composition by the A atoms and m% of B atoms number in n% of the total atoms means.
【0042】図4に第1実施例のカー回転角のヒステリ
シス特性を示す。図4において、は再生層4によるヒ
ステリシスループであり、は中間層5によるヒステリ
シスループである。FIG. 4 shows the hysteresis characteristic of the Kerr rotation angle of the first embodiment. FIG. 4 shows a hysteresis loop formed by the reproducing layer 4 and a hysteresis loop formed by the intermediate layer 5.
【0043】図4に示すように、再生層4によるヒステ
リシスループは中間層5によるヒステリシスループと完
全に分離している。このように第1実施例によれば、式
(5)の組成の中間補助層6の作用により中間層5と記
録層7との交換結合力が高まり、記録層7から再生層4
への磁化の転写を良好に行うことができる。さらに、本
実施例の中間層5は再生層4と良好な交換結合力を示す
ので、ディスク1は高いC/Nを示す。As shown in FIG. 4, the hysteresis loop of the reproducing layer 4 is completely separated from the hysteresis loop of the intermediate layer 5. As described above, according to the first embodiment, the exchange coupling force between the intermediate layer 5 and the recording layer 7 is increased by the action of the intermediate auxiliary layer 6 having the composition of the formula (5), and
Transfer of magnetization to the substrate can be performed satisfactorily. Further, since the intermediate layer 5 of the present embodiment has a good exchange coupling force with the reproducing layer 4, the disc 1 has a high C / N.
【0044】例えば、従来技術で説明した測定条件にお
いて、本実施例の光ディスク1は、38〔dB〕のC/N
を示し理想的なディスクの特性に近い良好な特性を示
す。 (ii)第2実施例 本発明の第2実施例は、第1実施例において説明した各
磁性層の組成において、中間補助層6の別の組成例を示
している。For example, under the measurement conditions described in the prior art, the optical disc 1 of the present embodiment has a C / N of 38 [dB].
And good characteristics close to those of an ideal disk. (Ii) Second Embodiment The second embodiment of the present invention shows another composition example of the intermediate auxiliary layer 6 in the composition of each magnetic layer described in the first embodiment.
【0045】図3に第2実施例の光磁気記録媒体の断面
図を示す。図3に示すように、第2実施例の光ディスク
11は、中間補助層6の組成を除いて、第1実施例と同
じ組成、膜厚条件の各磁性層を用いている。FIG. 3 shows a sectional view of the magneto-optical recording medium of the second embodiment. As shown in FIG. 3, the optical disk 11 of the second embodiment uses the magnetic layers having the same composition and thickness conditions as those of the first embodiment except for the composition of the intermediate auxiliary layer 6.
【0046】第2実施例の中間補助層6の組成比は、 (Tb3 Dy97)19(Fe90Co10)81〔at% 〕 …(6) である。The composition ratio of the intermediate auxiliary layer 6 in the second embodiment is (Tb 3 Dy 97 ) 19 (Fe 90 Co 10 ) 81 [at%] (6).
【0047】図5に第2実施例のカー回転角のヒステリ
シス特性を示す。図5において、は再生層4によるヒ
ステリシスループである。本実施例では、中間層5によ
るヒステリシスループは図5の特性図の範囲から大きく
外れているので、図示されていない。FIG. 5 shows the hysteresis characteristic of the Kerr rotation angle of the second embodiment. FIG. 5 shows a hysteresis loop by the reproducing layer 4. In the present embodiment, the hysteresis loop by the intermediate layer 5 is not illustrated because it is largely out of the range of the characteristic diagram of FIG.
【0048】上記のように第2実施例の光ディスク11
は高いC/Nを示す。例えば、従来技術で説明した測定
条件において、本実施例の光ディスク11は、第1実施
例と同じく、38〔dB〕のC/Nを示し理想的なディス
クの特性に近い良好な特性を示す。その他の変形例 以上の各実施例は、種々変更が可能である。As described above, the optical disk 11 of the second embodiment
Indicates a high C / N. For example, under the measurement conditions described in the prior art, the optical disk 11 of the present embodiment exhibits a C / N of 38 [dB] and exhibits good characteristics close to the characteristics of an ideal disk, as in the first embodiment. Other Modifications The above embodiments can be variously modified.
【0049】例えば、本実施例はFAD方式で行われた
が、RAD方式、さらに光スポットの低温領域、中温領
域及び高温領域を利用するいわゆるダブルマスク方式に
も適用できる。則ち、磁気的交換結合を行う必要のある
2つの磁性層を有する光ディスクにおいて、両者の交換
結合力を高めることにより所定の特性を光ディスクに持
たせることを希望する際には、この2層間に本発明の第
3の磁性層を介装させればよい。この結果、本発明の作
用により2層間の交換結合力が増大し、希望する磁気的
特性を有する光ディスクを生成することができる。For example, although the present embodiment is performed by the FAD system, the present invention can also be applied to the so-called double mask system using the low, middle and high temperature regions of the light spot. In other words, in an optical disc having two magnetic layers that need to perform magnetic exchange coupling, when it is desired that the optical disc has a predetermined characteristic by increasing the exchange coupling force between the two layers, it is desirable that the two layers be disposed between the two layers. What is necessary is just to interpose the third magnetic layer of the present invention. As a result, the exchange coupling force between the two layers is increased by the operation of the present invention, and an optical disk having desired magnetic characteristics can be produced.
【0050】また、本実施例では、磁気光学的偏光面回
転としてカー回転を利用していたが、各磁性層の膜厚を
調整し光を透過可能に設ければ、透過光を利用するファ
ラデー効果を利用した光ディスクにも適用できる。In this embodiment, the Kerr rotation is used as the magneto-optical polarization plane rotation. However, if the thickness of each magnetic layer is adjusted so that light can be transmitted, Faraday using transmitted light can be used. The present invention can also be applied to an optical disk utilizing the effect.
【0051】[0051]
【発明の効果】本願発明によれば、プラチナ(Pt)を
主成分とする金属とコバルト(Co)を主成分とする金
属との積層膜または合金膜を再生層とする光磁気記録媒
体において、第3の磁性層(中間補助膜)が第1の磁性
層(中間層)及び第2の磁性層(記録層)の組成を共に
備えて組成されるので、再生層と第1の磁性層(中間
層)との交換結合力が大きくなる第1の磁性層の組成に
おいても、第1の磁性層と第2の磁性層との交換結合力
が増大できる。そして、再生温度Tpb以上で第1の磁性
層の磁化は消失するので、FAD方式の再生が高いC/
Nで行うことができる。According to the present invention, there is provided a magneto-optical recording medium having a reproduction layer of a laminated film or an alloy film of a metal mainly composed of platinum (Pt) and a metal mainly composed of cobalt (Co). Since the third magnetic layer (intermediate auxiliary film) has both the composition of the first magnetic layer (intermediate layer) and the composition of the second magnetic layer (recording layer), the reproducing layer and the first magnetic layer ( The exchange coupling force between the first magnetic layer and the second magnetic layer can be increased even in the composition of the first magnetic layer in which the exchange coupling force with the intermediate layer increases. Then, since the magnetization of the first magnetic layer disappears at the reproduction temperature T pb or higher, the C / F of the FAD system is high in reproduction.
N.
【図1】本発明の再生原理図である。FIG. 1 is a diagram showing the principle of reproduction according to the present invention.
【図2】第1実施例の光磁気記録媒体の断面図である。FIG. 2 is a sectional view of the magneto-optical recording medium of the first embodiment.
【図3】第2実施例の光磁気記録媒体の断面図である。FIG. 3 is a sectional view of a magneto-optical recording medium according to a second embodiment.
【図4】第1実施例のカー回転角のヒステリシス特性図
である。FIG. 4 is a diagram illustrating a hysteresis characteristic of a car rotation angle according to the first embodiment.
【図5】第2実施例の中間層にDyFeCoを使用した
場合のカー回転角のヒステリシス特性図である。FIG. 5 is a hysteresis characteristic diagram of the Kerr rotation angle when DyFeCo is used for the intermediate layer of the second embodiment.
【図6】従来のFAD方式の光磁気記録媒体の断面図で
あり、(A)は第1の従来例(中間層にTbFeを使
用)、(B)は第2の従来例(中間層にDyFeCoを
使用)である。6A and 6B are cross-sectional views of a conventional FAD type magneto-optical recording medium, wherein FIG. 6A is a first conventional example (using TbFe for an intermediate layer), and FIG. 6B is a second conventional example (for an intermediate layer). DyFeCo).
【図7】FADの情報読出原理の説明図である。FIG. 7 is an explanatory diagram of the principle of reading information by the FAD.
【図8】第1の従来例(中間層にTbFeを使用)のカ
ー回転角のヒステリシス特性図である。FIG. 8 is a hysteresis characteristic diagram of the Kerr rotation angle of the first conventional example (using TbFe for the intermediate layer).
【図9】第2の従来例(中間層にDyFeCoを使用)
のカー回転角のヒステリシス特性図である。FIG. 9 shows a second conventional example (using DyFeCo for the intermediate layer).
FIG. 4 is a hysteresis characteristic diagram of the Kerr rotation angle of FIG.
1、11…光ディスク 1’、1”…従来の光ディスク 2、12…基板 3、13…下地層 4、14…再生層 5、15…中間層 6、16…中間補助層 7、17…記録層 8、18…保護層 51、61…基板 52、62…下地層 53、63…再生層 54、64…中間層 55、65…記録層 56、66…保護層 AL …低温領域 AH …高温領域 LB…読出光スポット TC0〜TC3…キュリー温度 Tpb…再生温度 HWpb …再生層の交換結合力 HWmd …中間層の交換結合力 HCpb …再生層の保磁力 HCmd …中間層の保磁力1, 11 optical disk 1 ', 1 "conventional optical disk 2, 12 substrate 3, 13 underlayer 4, 14 reproduction layer 5, 15 intermediate layer 6, 16 intermediate auxiliary layer 7, 17 recording layer 8, 18 Protective layer 51, 61 Substrate 52, 62 Underlayer 53, 63 Reproducing layer 54, 64 Intermediate layer 55, 65 Recording layer 56, 66 Protective layer A L Low-temperature region A H High temperature region LB ... read spot T C0 through T C3 ... Curie temperature T pb ... regeneration temperature H Wpb ... exchange coupling force H Cpb exchange coupling force H WMD ... middle layer of the reproducing layer ... reproducing layer coercivity H Cmd ... intermediate layer Coercive force
Claims (1)
コバルト(Co)を主成分とする金属との積層構造又は
プラチナ(Pt)及びコバルト(Co)を主成分とする
合金構造からなる読出光の照射側に位置する磁性層を有
する光磁気記録媒体であって、 ジスプロシウム(Dy)を主成分とする希土類と、鉄
(Fe)及びコバルト(Co)を主成分とする遷移金属
との合金を主成分とし第1のキュリー温度TC1を有する
第1の磁性層と、 テルビウム(Tb)を主成分とする希土類と、鉄(F
e)及びコバルト(Co)を主成分とする遷移金属と、
の合金を主成分とし第2のキュリー温度TC2を有する第
2の磁性層と、 ジスプロシウム(Dy)及びテルビウム(Tb)を共に
含有する希土類と、鉄(Fe)及びコバルト(Co)を
主成分とする遷移金属と、の合金を主成分とし第3のキ
ュリー温度TC3を有し前記第1の磁性層と前記第2の磁
性層との間に介装される第3の磁性層と、を有し、 前記第1の磁性層のキュリー温度TC1、前記第2の磁性
層のキュリー温度TC2、前記第3の磁性層のキュリー温
度TC3及び再生温度Tpbとの間にTC1<Tpb<TC2かつ
TC1≦TC3≦TC2なる関係を有すること、 を特徴とする光磁気記録媒体。1. A readout comprising a laminated structure of a metal mainly composed of platinum (Pt) and a metal mainly composed of cobalt (Co) or an alloy structure mainly composed of platinum (Pt) and cobalt (Co). A magneto-optical recording medium having a magnetic layer positioned on the light irradiation side, comprising: an alloy of a rare earth mainly composed of dysprosium (Dy) and a transition metal mainly composed of iron (Fe) and cobalt (Co). A first magnetic layer having a first Curie temperature T C1 as a main component, a rare earth element having terbium (Tb) as a main component, and iron (F
e) and a transition metal based on cobalt (Co);
A second magnetic layer having a second Curie temperature T C2 as a main component, a rare earth element containing both dysprosium (Dy) and terbium (Tb), and iron (Fe) and cobalt (Co) as main components. A third magnetic layer mainly composed of an alloy of a transition metal having the third Curie temperature T C3 and interposed between the first magnetic layer and the second magnetic layer; has the first Curie temperature T C1 of the magnetic layer, the Curie temperature T C2 of the second magnetic layer, the third T C1 between the Curie temperature T C3 and the regeneration temperature T pb of the magnetic layer <T pb <T C2 and T C1 ≦ T C3 ≦ T C2 .
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18951294A JP3243126B2 (en) | 1994-08-11 | 1994-08-11 | Magneto-optical recording medium |
US08/512,978 US5627803A (en) | 1994-08-11 | 1995-08-09 | Magneto optical recording medium including a plurality of magnetic layers and a method for reducing thereof |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18951294A JP3243126B2 (en) | 1994-08-11 | 1994-08-11 | Magneto-optical recording medium |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0855372A JPH0855372A (en) | 1996-02-27 |
JP3243126B2 true JP3243126B2 (en) | 2002-01-07 |
Family
ID=16242518
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP18951294A Expired - Fee Related JP3243126B2 (en) | 1994-08-11 | 1994-08-11 | Magneto-optical recording medium |
Country Status (2)
Country | Link |
---|---|
US (1) | US5627803A (en) |
JP (1) | JP3243126B2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3215311B2 (en) * | 1995-12-19 | 2001-10-02 | シャープ株式会社 | Magneto-optical recording medium and magneto-optical recording method |
US6118736A (en) * | 1997-09-25 | 2000-09-12 | Tosoh Corporation | Magneto-optical recording medium having a reading layer in which transferred recording marks are extended |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR970002341B1 (en) * | 1987-11-30 | 1997-03-03 | 소니 가부시끼가이샤 | Method for reproducing signal from magneto-optical |
US5168482A (en) * | 1989-08-31 | 1992-12-01 | Sony Corporation | Magnetooptical recording and playback method employing multi-layer recording medium with record holding layer and playback layer |
US5420728A (en) * | 1990-03-24 | 1995-05-30 | Seiko Epson Corporation | Magneto-optical recording medium including a plurality of recording layers having different curie temperatures and method of recording and reading |
JP2910250B2 (en) * | 1990-12-27 | 1999-06-23 | ソニー株式会社 | Magneto-optical recording medium |
US5241520A (en) * | 1990-12-28 | 1993-08-31 | Sony Corporation | System and method of reproducing signals recorded on a magneto-optic recording medium |
JPH05101472A (en) * | 1991-10-09 | 1993-04-23 | Sony Corp | Magneto-optical recording and reproducing system |
-
1994
- 1994-08-11 JP JP18951294A patent/JP3243126B2/en not_active Expired - Fee Related
-
1995
- 1995-08-09 US US08/512,978 patent/US5627803A/en not_active Expired - Fee Related
Also Published As
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JPH0855372A (en) | 1996-02-27 |
US5627803A (en) | 1997-05-06 |
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